1. Field of the Invention
The present invention relates to recording devices, video output devices, video display/record systems, and signal processing methods for video display/record systems, and particularly to a recording device, a video output device, a video display/record system, and a signal processing method for the video display/record system capable of identifying devices connected to the video output device.
2. Description of the Background Art
Example of a common device for outputting RGB video is a video system adapted to the DDC (Display Data Channel) standard (fully described later), whereby a video I/F system which is adopted in a personal computer system or the like and is capable of outputting video signals and making bi-directional communication between a video display device and a video output device.
Such a video system includes video output equipment having a plurality of video output modes to limit the video signal output mode according to performance specifications of the display device connected thereto more specifically, the video output. Equipment can change the displayable range of the video signal in accordance with specifications of the display device.
The above-mentioned DDC standard by VESA (Video Electronics Standard Associate) will now be described. The DDC standard is a system for enabling equipment (e.g., a display device) connected to the RGB terminal of a computer to send information including the displayable resolution range of the monitor to the computer.
Suppose that video outputted to the analog RGB output terminal of the video output device, such as a computer, is recorded. In this case, the devices may be connected as shown in FIG. 8, for example.
FIG. 8 shows a conventional structure for connecting a video display device and a video output device, wherein the video output device and the display device are directly connected, with a recording device additionally connected on the connecting line therebetween.
In FIG. 8, the reference numeral 1 denotes a recording device capable of recording analog RGB video signal, 11 denotes a recording an signal processing portion for applying recording processing to the video signal, 12 denotes a video signal converting portion, 13 denotes a recording operation inputting portion for input a recording command signal, and 14 denotes a switching portion for switching the input of the video signal based on the recording command signal. The reference numeral 2 denotes a video display device for displaying the video signal, 21 denotes an identification signal generating portion for outputting an identification signal (hereinafter referred to as an ID signal) indicating performance etc. of the video display device, 22 denotes a video signal processing portion, and 23 denotes a video signal display portion. The reference numeral 5 denotes a storage medium in which at least digital information by such as video information is stored, which is a recording disk, for example. The reference numeral 6 denotes a reconstructing device for reconstructing the digital signal from storage medium, e.g, the recording disk 5.
The reference numeral 3 denotes the body of a computer, 31 denotes a digital reconstruction processing portion for performing signal processing on the signal reconstructed in the reconstructing device 6, and 32 denotes a CPU (Central Processing Unit) for controlling the computer. The reference numeral 4 denotes an analog video signal output processing portion provided in the computer 3 for performing processing such as analog conversion to the digital video signal, 41 denotes an identification signal distinguishing portion for identifying an ID signal inputted from external equipment connected to the computer 3, 42 denotes a video data analog converting portion for applying analog conversion processing to the digital signal reconstructed from the recording disk 5, and 43 denotes a screen display resolution setting portion for setting the screen display resolution according to the range of the video signal which the display device can display.
Next, operation of the above structure is described. When recording the video signal outputted from the analog RGB terminal of the video output device, or the computer, the devices may be connected as shown in FIG. 8.
Described here is a process in which the video signal outputted from the analog video signal output portion 4 of the computer 3, or the video output device, is converted into a signal which is recordable in the recording device and then recorded.
In the case of the video display/record system shown in FIG. 8, the ID signal outputted from the identification signal generating portion 21 in the display device 2 by the DDC system is inputted into the computer 3. This enables the computer 3 to select a video signal within range displayable by the display device 3. When a previously set display resolution is out of the range, the closest resolution is selected in the range to output the video signal.
As stated above, in a conventional video input/output system formed of the computer 3, the recording device 1, and the video display device 2, the equipment connected to the computer 3 is recognized as a video display device by the DDC system and therefore the displayable range (resolution, frequencies of vertical/horizontal synchronizing signals, etc.) of the video signal outputted from the computer 3 is adapted to the specification of the video display device. Accordingly, the video signal may be outputted from the computer 3 in a display range (resolution, frequencies of vertical/horizontal synchronizing signals) which cannot be recorded by the recording device. This causes a first problem that, when recording with a recording device, it is necessary to provide a command, via the CPU 32, to the screen display resolution setting portion 43 to change the displayable range of the video signal outputted from the computer 3 to such video signal as can be inputted to the recording device.
Furthermore, even if the recording disk 5 is copy-protected, the analog RGB video signal is always outputted from the analog video signal output processing portion 4. The analog RGB video signal outputted from the analog video signal output processing portion 4 can therefore be inputted to the recording device, which causes a second problem in that the recording device 1 can easily record or copy the video signal even if the video source outputted from the analog video signal output processing portion 4 (the video output device) is copy-inhibited to protect copyright or secret information.